Detection of different target-DNA concentrations with highly sensitive AlGaN/GaN high electron mobility transistors

This paper presents the successful detection of different target-DNA concentrations using AlGaN/GaN high electron mobility field effect transistors (HEMTs). The gate was bio-functionalized with two different densities of complementary DNA before application of target-DNA. Dosages of 10-16 mol/L up to the gate saturation were tested. The DNA concentration was increased by a factor of 10 each time, and the transistor transfer characteristics were measured. The threshold voltage shift and drain-source current change depend on target concentration and obey the Sips adsorption model. The AlGaN/GaN HEMTs are highly sensitive to very low target-DNA concentrations with a detection limit of 10-14 mol/L. The gates with a low probe-DNA density were saturated with a lower target-DNA concentration and presented a faster hybridization equilibrium constant.